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Dolton G, Rius C, Hasan MS, Wall A, Szomolay B, Behiry E, Whalley T, Southgate J, Fuller A, Morin T, Topley K, Tan LR, Goulder PJR, Spiller OB, Rizkallah PJ, Jones LC, Connor TR, Sewell AK. Emergence of immune escape at dominant SARS-CoV-2 killer T cell epitope. Cell 2022; 185:2936-2951.e19. [PMID: 35931021 PMCID: PMC9279490 DOI: 10.1016/j.cell.2022.07.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 05/08/2022] [Accepted: 07/07/2022] [Indexed: 01/06/2023]
Abstract
We studied the prevalent cytotoxic CD8 T cell response mounted against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Spike glycoprotein269-277 epitope (sequence YLQPRTFLL) via the most frequent human leukocyte antigen (HLA) class I worldwide, HLA A∗02. The Spike P272L mutation that has arisen in at least 112 different SARS-CoV-2 lineages to date, including in lineages classified as "variants of concern," was not recognized by the large CD8 T cell response seen across cohorts of HLA A∗02+ convalescent patients and individuals vaccinated against SARS-CoV-2, despite these responses comprising of over 175 different individual T cell receptors. Viral escape at prevalent T cell epitopes restricted by high frequency HLAs may be particularly problematic when vaccine immunity is focused on a single protein such as SARS-CoV-2 Spike, providing a strong argument for inclusion of multiple viral proteins in next generation vaccines and highlighting the need for monitoring T cell escape in new SARS-CoV-2 variants.
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Affiliation(s)
- Garry Dolton
- Division of Infection and Immunity, Cardiff University School of Medicine, CF14 4XN Cardiff, Wales, UK
| | - Cristina Rius
- Division of Infection and Immunity, Cardiff University School of Medicine, CF14 4XN Cardiff, Wales, UK
| | - Md Samiul Hasan
- Division of Infection and Immunity, Cardiff University School of Medicine, CF14 4XN Cardiff, Wales, UK
| | - Aaron Wall
- Division of Infection and Immunity, Cardiff University School of Medicine, CF14 4XN Cardiff, Wales, UK
| | - Barbara Szomolay
- Division of Infection and Immunity, Cardiff University School of Medicine, CF14 4XN Cardiff, Wales, UK; Systems Immunology Research Institute, Cardiff University, CF14 4XN Cardiff, Wales, UK
| | - Enas Behiry
- Division of Infection and Immunity, Cardiff University School of Medicine, CF14 4XN Cardiff, Wales, UK
| | - Thomas Whalley
- School of Biosciences, Cardiff University, CF10 3AX Cardiff, Wales, UK
| | - Joel Southgate
- School of Biosciences, Cardiff University, CF10 3AX Cardiff, Wales, UK
| | - Anna Fuller
- Division of Infection and Immunity, Cardiff University School of Medicine, CF14 4XN Cardiff, Wales, UK
| | - Théo Morin
- Division of Infection and Immunity, Cardiff University School of Medicine, CF14 4XN Cardiff, Wales, UK
| | - Katie Topley
- Division of Infection and Immunity, Cardiff University School of Medicine, CF14 4XN Cardiff, Wales, UK
| | - Li Rong Tan
- Division of Infection and Immunity, Cardiff University School of Medicine, CF14 4XN Cardiff, Wales, UK
| | - Philip J R Goulder
- Department of Paediatrics, University of Oxford, OX3 9DU Oxford, England, UK
| | - Owen B Spiller
- Division of Infection and Immunity, Cardiff University School of Medicine, CF14 4XN Cardiff, Wales, UK
| | - Pierre J Rizkallah
- Division of Infection and Immunity, Cardiff University School of Medicine, CF14 4XN Cardiff, Wales, UK
| | - Lucy C Jones
- Division of Infection and Immunity, Cardiff University School of Medicine, CF14 4XN Cardiff, Wales, UK; Centre for Clinical Research, Royal Glamorgan Hospital, Ynysmaerdy CF72 8XR, UK
| | - Thomas R Connor
- Systems Immunology Research Institute, Cardiff University, CF14 4XN Cardiff, Wales, UK; School of Biosciences, Cardiff University, CF10 3AX Cardiff, Wales, UK; Pathogen genomics Unit, Public Health Wales NHS Trust, CF14 4XW Cardiff, Wales, UK.
| | - Andrew K Sewell
- Division of Infection and Immunity, Cardiff University School of Medicine, CF14 4XN Cardiff, Wales, UK; Systems Immunology Research Institute, Cardiff University, CF14 4XN Cardiff, Wales, UK.
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Identification of novel HLA-A11-restricted T-cell epitopes in the Ebola virus nucleoprotein. Microbes Infect 2018; 21:56-62. [PMID: 29775667 DOI: 10.1016/j.micinf.2018.04.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 04/20/2018] [Accepted: 04/26/2018] [Indexed: 12/17/2022]
Abstract
The Ebola virus (EBOV) is a very contagious virus that is highly fatal in humans and animals. The largest epidemic was in West Africa in 2014, in which over 11,000 people died. However, to date, there are no licensed vaccines against it. Studies show that CD4+ and CD8+ T-cell responses, especially cytotoxic T-lymphocyte (CTL) responses, play key roles in protecting individuals from EBOV infection. Since HLA-restricted epitope vaccines are likely to be effective and safe immunization strategies for infectious diseases, the present study screened for CTL epitopes in the EBOV-nucleoprotein that are restricted by HLA-A11 (a common allele in Chinese people). Predictive computer analysis of the amino-acid sequence of EBOV-nucleoprotein identified ten putative HLA-A11-restricted epitopes. ELISPOT assay of immunized HLA-A11/DR1 transgenic mice showed that five (GR-9, VR-9, EK-9, PK-9, and RK-9) induced effective CTL responses. Additional epitope analyses will aid the design of epitope vaccines against EBOV.
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Abstract
Background Ebolavirus (EBOV) is responsible for one of the most fatal diseases encountered by mankind. Cellular T-cell responses have been implicated to be important in providing protection against the virus. Antigenic variation can result in viral escape from immune recognition. Mapping targets of immune responses among the sequence of viral proteins is, thus, an important first step towards understanding the immune responses to viral variants and can aid in the identification of vaccine targets. Herein, we performed a large-scale, proteome-wide mapping and diversity analyses of putative HLA supertype-restricted T-cell epitopes of Zaire ebolavirus (ZEBOV), the most pathogenic species among the EBOV family. Methods All publicly available ZEBOV sequences (14,098) for each of the nine viral proteins were retrieved, removed of irrelevant and duplicate sequences, and aligned. The overall proteome diversity of the non-redundant sequences was studied by use of Shannon’s entropy. The sequences were predicted, by use of the NetCTLpan server, for HLA-A2, -A3, and -B7 supertype-restricted epitopes, which are relevant to African and other ethnicities and provide for large (~86%) population coverage. The predicted epitopes were mapped to the alignment of each protein for analyses of antigenic sequence diversity and relevance to structure and function. The putative epitopes were validated by comparison with experimentally confirmed epitopes. Results & discussion ZEBOV proteome was generally conserved, with an average entropy of 0.16. The 185 HLA supertype-restricted T-cell epitopes predicted (82 (A2), 37 (A3) and 66 (B7)) mapped to 125 alignment positions and covered ~24% of the proteome length. Many of the epitopes showed a propensity to co-localize at select positions of the alignment. Thirty (30) of the mapped positions were completely conserved and may be attractive for vaccine design. The remaining (95) positions had one or more epitopes, with or without non-epitope variants. A significant number (24) of the putative epitopes matched reported experimentally validated HLA ligands/T-cell epitopes of A2, A3 and/or B7 supertype representative allele restrictions. The epitopes generally corresponded to functional motifs/domains and there was no correlation to localization on the protein 3D structure. These data and the epitope map provide important insights into the interaction between EBOV and the host immune system. Electronic supplementary material The online version of this article (10.1186/s12864-017-4328-8) contains supplementary material, which is available to authorized users.
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Varela-Rohena A, Molloy PE, Dunn SM, Li Y, Suhoski MM, Carroll RG, Milicic A, Mahon T, Sutton DH, Laugel B, Moysey R, Cameron BJ, Vuidepot A, Purbhoo MA, Cole DK, Phillips RE, June CH, Jakobsen BK, Sewell AK, Riley JL. Control of HIV-1 immune escape by CD8 T cells expressing enhanced T-cell receptor. Nat Med 2008; 14:1390-5. [PMID: 18997777 DOI: 10.1038/nm.1779] [Citation(s) in RCA: 193] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Accepted: 04/28/2008] [Indexed: 11/09/2022]
Abstract
HIV's considerable capacity to vary its HLA-I-restricted peptide antigens allows it to escape from host cytotoxic T lymphocytes (CTLs). Nevertheless, therapeutics able to target HLA-I-associated antigens, with specificity for the spectrum of preferred CTL escape mutants, could prove effective. Here we use phage display to isolate and enhance a T-cell antigen receptor (TCR) originating from a CTL line derived from an infected person and specific for the immunodominant HLA-A(*)02-restricted, HIVgag-specific peptide SLYNTVATL (SL9). High-affinity (K(D) < 400 pM) TCRs were produced that bound with a half-life in excess of 2.5 h, retained specificity, targeted HIV-infected cells and recognized all common escape variants of this epitope. CD8 T cells transduced with this supraphysiologic TCR produced a greater range of soluble factors and more interleukin-2 than those transduced with natural SL9-specific TCR, and they effectively controlled wild-type and mutant strains of HIV at effector-to-target ratios that could be achieved by T-cell therapy.
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Affiliation(s)
- Angel Varela-Rohena
- Department of Pathology and Laboratory Medicine, Abramson Family Cancer Research Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6160, USA
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Guillon C, Stankovic K, Ataman-Onal Y, Biron F, Verrier B. Evidence for CTL-mediated selection of Tat and Rev mutants after the onset of the asymptomatic period during HIV type 1 infection. AIDS Res Hum Retroviruses 2006; 22:1283-92. [PMID: 17209772 DOI: 10.1089/aid.2006.22.1283] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The evolution of HIV-1 sequences over time is the result of the selection of mutant variants that have escaped from host immune responses or the outgrowth of mutants with increased viral replication, or both. We investigated the contribution of both selection processes to the overall evolution of the Tat and Rev regulatory gene sequences from four individuals, ranging in time from just prior to seroconversion to stable asymptomatic infection. After sequencing at least 15 clones per sample per gene, we analyzed the sequence evolution of the MHC-I motifs that were predicted from the MHC-I haplotypes of these patients. For each identified Tat sequence, we tested the activity of the corresponding encoded protein in a transactivation assay in vitro. Our results suggest that the evolution of the Tat and Rev sequences from these individuals can be explained by mutational escape of the MHC-I epitopes and that no mutations that replaced the original sequences in the viral population are associated with either an increase or decrease in Tat activity. CTL-mediated selection appears to be an important determinant of HIV-1 regulatory gene sequence evolution during the early stages of infection.
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MESH Headings
- Amino Acid Sequence
- Epitopes
- Evolution, Molecular
- Gene Products, rev/genetics
- Gene Products, rev/immunology
- Gene Products, tat/genetics
- Gene Products, tat/immunology
- Genes, rev/genetics
- Genes, rev/immunology
- Genes, tat/immunology
- HIV Infections/genetics
- HIV Seropositivity/genetics
- HIV Seropositivity/virology
- HIV-1/genetics
- Humans
- Molecular Sequence Data
- Selection, Genetic
- Sequence Alignment
- T-Lymphocytes, Cytotoxic/virology
- Virus Replication
- rev Gene Products, Human Immunodeficiency Virus
- tat Gene Products, Human Immunodeficiency Virus
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Affiliation(s)
- C Guillon
- CNRS, FRE2736 CNRS/bioMérieux, IFR128 Biosciences-Lyon Gerland, Tour CERVI, 69007 Lyon, France.
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Zimbwa P, Milicic A, Frater J, Scriba TJ, Willis A, Goulder PJR, Pillay T, Gunthard H, Weber JN, Zhang HT, Phillips RE. Precise identification of a human immunodeficiency virus type 1 antigen processing mutant. J Virol 2006; 81:2031-8. [PMID: 17108020 PMCID: PMC1797578 DOI: 10.1128/jvi.00968-06] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) evokes a strong immune response, but the virus persists. Polymorphisms within known antigenic sites result in loss of immune recognition and can be positively selected. Amino acid variation outside known HLA class I restricted epitopes can also enable immune escape by interfering with the processing of the optimal peptide antigen. However, the lack of precise rules dictating epitope generation and the enormous genetic diversity of HIV make prediction of processing mutants very difficult. Polymorphism E169D in HIV-1 reverse transcriptase (RT) is significantly associated with HLA-B*0702 in HIV-1-infected individuals. This polymorphism does not map within a known HLA-B*0702 epitope; instead, it is located five residues downstream of a HLA-B*0702-restricted epitope SPAIFQSSM (SM9). Here we investigate the association between E169D and HLA-B*0702 for immune escape via the SM9 epitope. We show that this single amino acid variation prevents the immune recognition of the flanked SM9 epitope by cytotoxic T cells through lack of generation of the epitope, which is a result of aberrant proteasomal cleavage. The E169D polymorphism also maps within and abrogates the recognition of an HLA-A*03-restricted RT epitope MR9. This study highlights the potential for using known statistical associations as indicators for viral escape but also the complexity involved in interpreting the immunological consequences of amino acid changes in HIV sequences.
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Affiliation(s)
- Peter Zimbwa
- The James Martin 21st Century School at The Peter Medawar Building for Pathogen Research, Nuffield Department of Clinical Medicine, University of Oxford, South Parks Road, Oxford OX1 3SY, United Kingdom
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7
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López M, Soriano V, Lozano S, Martinez P, Sempere J, González-Lahoz J, Benito J. Impact of Gag sequence variability on level, phenotype, and function of anti-HIV Gag-specific CD8(+) cytotoxic T lymphocytes in untreated chronically HIV-infected patients. AIDS Res Hum Retroviruses 2006; 22:884-92. [PMID: 16989614 DOI: 10.1089/aid.2006.22.884] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
The role of cytotoxic T lymphocyte responses in controlling viral replication during chronic HIV infection remains controversial. Viral escape mutations driven by immune pressure have been postulated to be an important mechanism contributing to the evasion of CD8(+) T cell responses. To explore this issue in more detail, HIV-1 p17 sequence variability was examined in chronically HIV-infected patients, in parallel with the level, phenotype, and function of HIV-SL9-specific CD8(+) T cell. Thirty-one HLA-A*0201(+) (A2(+)) and 10 HLAA* 02() (A2()) patients were included. The phenotype of SL9-specific CD8(+) T cell and their ability to produce IFN-gamma were analyzed by multiparameter flow cytometry. The HIV Gag p17 was sequenced and the mean variability score for each residue within SL9 and the two epitope flanking regions were calculated using Shannon entropy. The mean variability of SL9 and the proportion of patients with amino acid changes within SL9 were similar in A2(+) and A2() patients. Patients without Tet(+) cells had a significantly higher prevalence of aminoacid changes in SL9 than patients with Tet(+) cells. Interestingly, in patients with Tet(+) cells, the Y79F mutation within SL9 tended to be associated with lower levels of Tet(+) cells. We did not find any association between amino acid changes within SL9 and the differentiation stage of Tet(+) cells, or with IFN-gamma production. A similar analysis within the epitope flanking sequences did not reveal differences in the variability of these regions. These results suggest that viral mutations driven by immune selection pressure may play an important role in evading the immunological response in chronically HIV-infected individuals.
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Affiliation(s)
- Mariola López
- Infectious Diseases and Haematology Unit, Hospital Carlos III, 28029 Madrid, Spain
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Boon ACM, de Mutsert G, Fouchier RAM, Osterhaus ADME, Rimmelzwaan GF. The hypervariable immunodominant NP418-426 epitope from the influenza A virus nucleoprotein is recognized by cytotoxic T lymphocytes with high functional avidity. J Virol 2006; 80:6024-32. [PMID: 16731941 PMCID: PMC1472604 DOI: 10.1128/jvi.00009-06] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Recently it was shown that influenza A viruses can accumulate mutations in epitopes associated with escape from recognition by human virus-specific cytotoxic T lymphocytes (CTL). It is unclear what drives diversification of CTL epitopes and why certain epitopes are variable and others remain conserved. It has been shown that simian immunodeficiency virus-specific CTL that recognize their epitope with high functional avidity eliminate virus-infected cells efficiently and drive diversification of CTL epitopes. T-cell functional avidity is defined by the density of major histocompatibility complex class I peptide complexes required to activate specific CTL. We hypothesized that functional avidity of CTL contributes to epitope diversification and escape from CTL also for influenza viruses. To test this hypothesis, the functional avidity of polyclonal CTL populations specific for nine individual epitopes was determined. To this end, peripheral blood mononuclear cells from HLA-A- and -B-genotyped individuals were stimulated in vitro with influenza virus-infected cells to allow expansion of virus-specific CTL, which were used to determine the functional avidity of CTL specific for nine individual epitopes in enzyme-linked immunospot assays. We found that the functional avidity for the respective epitopes varied widely. Furthermore, the functional avidity of CTL specific for the hypervariable NP(418-426) epitope was significantly higher than that of CTL recognizing other epitopes (P < 0.01). It was speculated that the high functional avidity of NP(418-426)-specific CTL was responsible for the diversification of this influenza A virus CTL epitope.
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Affiliation(s)
- Adrianus C M Boon
- Department of Virology, Erasmus MC, P.O. Box 1738, 3000 DR Rotterdam, The Netherlands
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9
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Milicic A, Price DA, Zimbwa P, Booth BL, Brown HL, Easterbrook PJ, Olsen K, Robinson N, Gileadi U, Sewell AK, Cerundolo V, Phillips RE. CD8+ T cell epitope-flanking mutations disrupt proteasomal processing of HIV-1 Nef. THE JOURNAL OF IMMUNOLOGY 2005; 175:4618-26. [PMID: 16177107 DOI: 10.4049/jimmunol.175.7.4618] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CTL play a critical role in the control of HIV and SIV. However, intrinsic genetic instability enables these immunodeficiency viruses to evade detection by CTL through mutation of targeted antigenic sites. These mutations can impair binding of viral epitopes to the presenting MHC class I molecule or disrupt TCR-mediated recognition. In certain regions of the virus, functional constraints are likely to limit the capacity for variation within epitopes. Mutations elsewhere in the protein, however, might still enable immune escape through effects on Ag processing. In this study, we describe the coincident emergence of three mutations in a highly conserved region of Nef during primary HIV-1 infection. These mutations (R69K, A81G, and H87R) flank the HLA B*35-restricted VY8 epitope and persisted to fixation as the early CTL response to this Ag waned. The variant form of Nef showed a reduced capacity to activate VY8-specific CTL, although protein stability and expression levels were unchanged. This effect was associated with altered processing by the proteasome that caused partial destruction of the VY8 epitope. Our data demonstrate that a variant HIV genotype can significantly impair proteasomal epitope processing and substantiate the concept of immune evasion through diminished Ag generation. These observations also indicate that the scale of viral escape may be significantly underestimated if only intraepitope variation is evaluated.
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Affiliation(s)
- Anita Milicic
- James Martin 21st Century School and Nuffield Department of Clinical Medicine, The Peter Medawar Building, University of Oxford, Oxford, United Kingdom.
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Uhlin M, Sandalova E, Masucci MG, Levitsky V. Help signals provided by lymphokines modulate the activation and apoptotic programs induced by partially agonistic peptides in specific cytotoxic T lymphocytes. Eur J Immunol 2005; 35:2929-39. [PMID: 16163673 DOI: 10.1002/eji.200526330] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Inefficient recognition of altered peptide ligands (APL) by specific CTL is believed to contribute to the failure of immune control over tumors and progressive viral infections. A link between deficient help signals and the appearance of CTL epitope mutants has been suggested by recent studies. However, the regulation of APL activity by immunologic help is not well understood. We analyzed the capacity of exogenous IL-2 and IL-15, which are physiologically produced by cells of the adaptive and innate immune system, respectively, to modulate proliferation, responsiveness to repeated stimulation and apoptotic programs triggered in specific CTL by either fully or partially agonistic peptide ligands. We show that signals induced by the lymphokines synergize with weak TCR signaling induced by partially agonistic APL, converting many of these peptides from inhibitory to stimulatory ligands. Some APL partially suppress the responsiveness of specific CTL to secondary stimulation, while this inhibitory effect is diminished if APL-stimulated cells are cultured in the presence of either of the lymphokines. We also demonstrate that IL-2 and IL-15 suppress up-regulation of the Bcl-2 family member Bim and induction of a death receptor-independent apoptotic program triggered by partially agonistic APL. Our results suggest that under conditions of insufficient immunologic help, partially agonistic APL may actively suppress specific CTL responses and become especially advantageous for immune escape of tumors or viruses.
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Affiliation(s)
- Michael Uhlin
- Microbiology and Tumorbiology Center, Karolinska Institutet, Stockholm, Sweden
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11
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Berkhoff EGM, de Wit E, Geelhoed-Mieras MM, Boon ACM, Symons J, Fouchier RAM, Osterhaus ADME, Rimmelzwaan GF. Functional constraints of influenza A virus epitopes limit escape from cytotoxic T lymphocytes. J Virol 2005; 79:11239-46. [PMID: 16103176 PMCID: PMC1193597 DOI: 10.1128/jvi.79.17.11239-11246.2005] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Viruses can exploit a variety of strategies to evade immune surveillance by cytotoxic T lymphocytes (CTL), including the acquisition of mutations in CTL epitopes. Also for influenza A viruses a number of amino acid substitutions in the nucleoprotein (NP) have been associated with escape from CTL. However, other previously identified influenza A virus CTL epitopes are highly conserved, including the immunodominant HLA-A*0201-restricted epitope from the matrix protein, M1(58-66). We hypothesized that functional constraints were responsible for the conserved nature of influenza A virus CTL epitopes, limiting escape from CTL. To assess the impact of amino acid substitutions in conserved epitopes on viral fitness and recognition by specific CTL, we performed a mutational analysis of CTL epitopes. Both alanine replacements and more conservative substitutions were introduced at various positions of different influenza A virus CTL epitopes. Alanine replacements for each of the nine amino acids of the M1(58-66) epitope were tolerated to various extents, except for the anchor residue at the second position. Substitution of anchor residues in other influenza A virus CTL epitopes also affected viral fitness. Viable mutant viruses were used in CTL recognition experiments. The results are discussed in the light of the possibility of influenza viruses to escape from specific CTL. It was speculated that functional constraints limit variation in certain epitopes, especially at anchor residues, explaining the conserved nature of these epitopes.
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Affiliation(s)
- E G M Berkhoff
- Department of Virology, Erasmus Medical Center, Rotterdam, The Netherlands
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12
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Berkhoff EGM, Boon ACM, Nieuwkoop NJ, Fouchier RAM, Sintnicolaas K, Osterhaus ADME, Rimmelzwaan GF. A mutation in the HLA-B*2705-restricted NP383-391 epitope affects the human influenza A virus-specific cytotoxic T-lymphocyte response in vitro. J Virol 2004; 78:5216-22. [PMID: 15113903 PMCID: PMC400375 DOI: 10.1128/jvi.78.10.5216-5222.2004] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2003] [Accepted: 01/16/2004] [Indexed: 01/14/2023] Open
Abstract
Viruses can exploit a variety of strategies to evade immune surveillance by cytotoxic T lymphocytes (CTL), including the acquisition of mutations in or adjacent to CTL epitopes. Recently, an amino acid substitution (R384G) in an HLA-B*2705-restricted CTL epitope in the influenza A virus nucleoprotein (nucleoprotein containing residues 383 to 391 [NP(383-391)]; SRYWAIRTR, where R is the residue that was mutated) was associated with escape from CTL-mediated immunity. The effect of this mutation on the in vitro influenza A virus-specific CTL response was studied. To this end, two influenza A viruses, one with and one without the NP(383-391) epitope, were constructed by reverse genetics and designated influenza viruses A/NL/94-384R and A/NL/94-384G, respectively. The absence of the HLA-B*2705-restricted CTL epitope in influenza virus A/NL/94-384G was confirmed by using (51)Cr release assays with a T-cell clone specific for the NP(383-391) epitope. In addition, peripheral blood mononuclear cells (PBMC) stimulated with influenza virus A/NL/94-384G failed to recognize HLA-B*2705-positive target cells pulsed with the original NP(383-391) peptide. The proportion of virus-specific CD8+ gamma interferon (IFN-gamma)-positive T cells in in vitro-stimulated PBMC was determined by intracellular IFN-gamma staining after restimulation with virus-infected autologous B-lymphoblastoid cell lines and C1R cell lines expressing only HLA-B*2705. The proportion of virus-specific CD8+ T cells was lower in PBMC stimulated in vitro with influenza virus A/NL/94-384G obtained from several HLA-B*2705-positive donors than in PBMC stimulated with influenza virus A/NL/94-384R. This finding indicated that amino acid variations in CTL epitopes can affect the virus-specific CTL response and that the NP(383-391) epitope is the most important HLA-B*2705-restricted epitope in the nucleoprotein of influenza A viruses.
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Affiliation(s)
- E G M Berkhoff
- Institute of Virology, Erasmus Medical Center, 3000 DR Rotterdam, The Netherlands
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13
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Wang JH, Layden TJ, Eckels DD. Modulation of the peripheral T-Cell response by CD4 mutants of hepatitis C virus: transition from a Th1 to a Th2 response. Hum Immunol 2003; 64:662-73. [PMID: 12826368 DOI: 10.1016/s0198-8859(03)00070-3] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
A disturbing feature of hepatitis C virus (HCV) is its long-term persistence in roughly 85% of those infected. Escape mutants may play a major role in HCV persistence. Our previous studies have identified a human leukocyte antigen DRB1*15 (HLA-DRB1*15) restricted Th1 epitope in the HCV NS3 protein, NS3(358-375), and escape variants of this epitope that may emerge under immune selection. Such variants attenuate or fail to stimulate T-cell proliferation. Here we provide data from peripheral blood mononuclear cells derived from four HLA-DRB1*15 patients chronically infected with HCV, and report that naturally occurring single amino acid substitutions in the Th1 epitope NS3(358-375) fail to stimulate proliferation, which is accompanied by a shift in cytokine secretion patterns from one characteristic of a Th1 antiviral responses to a Th2 form. Further, in one patient, we demonstrate that HCV variant peptides can effectively inhibit host polyclonal peripheral T-cell proliferation. We speculate that this phenomenon may be a factor in chronic HCV infection.
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Affiliation(s)
- Jane H Wang
- Section of Liver Diseases, University of Illinois at Chicago, Chicago, IL, USA
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Moschella F, Ombra MN, Del Pozzo G, Guardiola J. Administration of different antigenic forms of altered peptide ligands derived from HIV-1 RTase influences their effects on T helper cell activation. Hum Immunol 2003; 64:1-8. [PMID: 12507809 DOI: 10.1016/s0198-8859(02)00783-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Genetic hypervariability of viruses such as HIV-1 facilitates appearance of escape mutants for immune response. HIV-1 isolates display variant epitopes, which may fail to stimulate T-lymphocyte responses or act as natural T-cell receptor antagonists, contributing to viral persistence. We evaluated the effect on epitope specific T-cell reactions of different amino acid substitutions in a residue of the 248-262 sequence of HIV-1 reverse transcriptase (peptide 23), showing variability in different viral isolates. Responses against such a determinant have been detected in long-term nonprogressive patients. The modified antigenic determinant was administered either as synthetic peptide or as recombinant protein. Our results show that certain amino acid substitutions abolished peptide binding to major histocompatibility complex (MHC); other modifications, although not affecting the formation of the MHC/peptide complex, either abrogated T-cell proliferation or exhibited an antagonistic effect. The results suggest that residue 11 of peptide 23 exhibits a double function; its alteration affects both the peptide affinity for the MHC and the MHC/peptide complex affinity for the T-cell receptor. Furthermore, we demonstrated that synthetic ligands and recombinant proteins may produce distinct functional effects, providing evidence that synthetic peptides, compared with corresponding epitopes generated by intracellular processing of recombinant proteins, may bind to the MHC groove in a different conformation.
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Affiliation(s)
- Federica Moschella
- Division of Medical Oncology, Department of Medicine of the College of Physicians and Surgeons of Columbia University, New York, New York, USA
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15
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Oxenius A, Sewell AK, Dawson SJ, Günthard HF, Fischer M, Gillespie GM, Rowland-Jones SL, Fagard C, Hirschel B, Phillips RE, Price DA. Functional discrepancies in HIV-specific CD8+ T-lymphocyte populations are related to plasma virus load. J Clin Immunol 2002; 22:363-74. [PMID: 12462336 DOI: 10.1023/a:1020656300027] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The potent ability of current antiretroviral drug regimens to control human immunodeficiency Virus-1 (HIV-1) replication, in conjunction with the clinical practice of structured therapeutic interruptions, provides a system in which virus levels are manipulated during a persistent infection in humans. Here, we exploit this system to examine the impact of variable plasma virus load (pVL) on the functionality of HIV-specific CD8+ T-lymphocyte populations. Using both ELISpot methodology and intracellular cytokine staining for interferon (IFN)-gamma to assess functional status, together with fluorochrome-labeled peptide-major histocompatibility complex (pMHC) class I tetramer analysis to detect the physical presence of CD8+ T lymphocytes expressing cognate T-cell receptors (TCRs), we observed that the proportion of HIV-specific CD8+ T lymphocytes capable of mounting an effector response to antigen challenge directly ex vivo is related to the kinetics of virus exposure. Specifically, (a) after prolonged suppression of pVL with antiretroviral therapy (ART), physical and functional measures of HIV-specific CD8+ T-lymphocyte frequencies approximated; and (b) the percentage of functionally responsive cells in the HIV-specific CD8+ T lymphocyte populations declined substantially when therapy was discontinued and pVL recrudesced in the same patients. These results corroborate and extend observations in animal models that describe nonresponsive CD8+ T lymphocytes in the presence of high levels of antigen load and have implications for the interpretation of quantitative data generated by methods that rely on functional readouts.
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Affiliation(s)
- Annetie Oxenius
- Nuffield Department of Clinical Medicine, University of Oxford, John Radcliffe Hospital, England.
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16
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Abstract
Bioinformatics-driven T-cell epitope-identification methods can enhance vaccine target selection significantly. We evaluated three unrelated computational methods to screen Pol, Gag and Env sequences extracted from the Los Alamos HIV database for HLA-A*0201 and HLA-B*3501 T-cell epitope candidates. The hidden Markov model predicted 389 HLA-B*3501-restricted candidates from 374 HIV-1 and 97 HIV-2 sequences. The artificial neural network (ANN) model, and Bioinformatics and Molecular Analysis Section (BIMAS) quantitative matrix predictions for A*0201 yielded 1122 HIV-1 and 548 HIV-2 candidates. The overall sequence coverage of the predicted A*0201 T-cell epitopes was 2.7% (HIV-1)and 3.0% (HIV-2). HLA-B*3501-predicted epitopes covered 0.9% (HIV-1) and 1.4% (HIV-2) of the total sequence. Comparison of 890 ANN- and 397 BIMAS-derived HIV-1 A*0201- restricted epitope candidates showed that only 13-19% of the predicted and 26% of the experimentally confirmed T-cell epitopes were captured by both methods. Extrapolating these results, we estimated that at least 247 predicted HIV-1 epitopes are yet to be discovered as active A*0201-restricted T-cell epitopes. Adequate comparison and combined usage of various predictive bioinformatics methods, rather than uncritical use of any single prediction method, will enable cost-effective and efficient T-cell epitope screening.
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17
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Boon ACM, de Mutsert G, Graus YMF, Fouchier RAM, Sintnicolaas K, Osterhaus ADME, Rimmelzwaan GF. Sequence variation in a newly identified HLA-B35-restricted epitope in the influenza A virus nucleoprotein associated with escape from cytotoxic T lymphocytes. J Virol 2002; 76:2567-72. [PMID: 11836437 PMCID: PMC153818 DOI: 10.1128/jvi.76.5.2567-2572.2002] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Here, we describe a new HLA-B*3501-restricted cytotoxic T lymphocyte (CTL) epitope in the influenza A virus (H3N2) nucleoprotein, which was found to exhibit a high degree of variation at nonanchor residues. The influenza virus variants emerged in chronological order, and CTLs directed against old variants failed to recognize more recent strains of influenza A virus, indicating an escape from CTL immunity.
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Affiliation(s)
- A C M Boon
- Institute of Virology, Erasmus University Rotterdam, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands
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18
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Affiliation(s)
- N Bitton
- Laboratoire d'Immunologie Cellulaire, CERVI, INSERM U543, Hopital Pitie-Salpetriere, 83 Bvd de l'Hopital, 75013 Paris, France
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19
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Oxenius A, Price DA, Dawson SJ, Tun T, Easterbrook PJ, Phillips RE, Sewell AK. Cross-staining of cytotoxic T lymphocyte populations with peptide-MHC class I multimers of natural HIV-1 variant antigens. AIDS 2001; 15:121-2. [PMID: 11192854 DOI: 10.1097/00002030-200101050-00018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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20
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Sewell AK, Price DA, Oxenius A, Kelleher AD, Phillips RE. Cytotoxic T lymphocyte responses to human immunodeficiency virus: control and escape. Stem Cells 2000; 18:230-44. [PMID: 10924089 DOI: 10.1634/stemcells.18-4-230] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Effective preventive and therapeutic intervention in individuals exposed to or infected with human immunodeficiency virus (HIV) depends, in part, on a clear understanding of the interactions between the virus and those elements of the host immune response which control viral replication. Recent advances have provided compelling evidence that cytotoxic T lymphocytes (CTLs) constitute an essential component of protective antiretroviral immunity. Here, we review briefly the significance of this work in the context of previous studies, and outline the mechanisms through which HIV evades CTL activity.
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Affiliation(s)
- A K Sewell
- The Nuffield Department of Medicine, John Radcliffe Hospital, Oxford, UK.
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21
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Pratelli A, Altamura M, Buonavoglia D, Pepe M, Tafaro A, Lembo A, Cirone F, Tempesta M, Jirillo E, Buonavoglia C. Evaluation of the natural immunity in pups inoculated with a modified-live canine parvovirus type 2b (CPV-2b) strain. Immunopharmacol Immunotoxicol 2000; 22:451-64. [PMID: 10946825 DOI: 10.3109/08923970009026005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Three pups 2-4 months old were vaccinated subcutaneously with the modified live canine parvovirus, CPV-2b/29-97 strain. During an observation period of two weeks pups remained clinically health, exhibiting a vigorous post-vaccinal active serological response (haemoagglutinating inhibiting antibody titers for CPV-2 ranging from 1:2560 to 1:5120 at 21 days post inoculation). Phagocytosis and killing of Candida albicans exerted by polymorphonuclear cells and monocytes did not undergo significant modifications 3-6 days post vaccination up to 30 days. Antibacterial activity mediated by peripheral blood lymphocytes (Salmonella typhi was used as a target) was slightly, but not significantly decreased 3 days post vaccination. Conclusively, in pups the CPV type 2b vaccine seems to be safe as far as natural immune responses are concerned, while its immunogenicity is preserved.
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Affiliation(s)
- A Pratelli
- Department of Health and Animal Welfare, Faculty of Veterinary Medicine, University of Bari, Valenzano, Italy
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22
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Dela Cruz CS, MacDonald KS, Barber BH. Anti-major histocompatibility complex antibody responses in macaques via intradermal DNA immunizations. Vaccine 2000; 18:3152-65. [PMID: 10856795 DOI: 10.1016/s0264-410x(00)00086-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In simian immunodeficiency virus (SIV) models, immunization of macaques with uninfected human cells or human major histocompatibility complex (MHC) proteins can induce xenogeneic immune responses which can protect the animals from subsequent SIV challenges. These studies suggest that the induction of anti-MHC immune responses can be a viable vaccine strategy against human immunodeficiency virus type 1 (HIV-1). We have previously shown in mouse studies that DNA immunization with class I and class II MHC-encoding plasmids can elicit both xenogeneic and allogeneic antibody responses against conformationally intact MHC molecules (Vaccine 17 (1999) 2479-92). Here we take these observations one step closer to human applications and report that intradermal needle immunizations of non-human primates with plasmid DNA encoding human MHC alleles can safely elicit xenogeneic anti-MHC antibody responses. Moreover, injecting macaques with DNA encoding a specific macaque allogeneic MHC induced anti-allogeneic MHC antibodies production. These studies show that DNA immunization with MHC-encoding vectors can indeed be used to induce specific anti-human xenogeneic, as well as anti-macaque allogeneic MHC immunity in non-human primates. This strategy could thus be used to mobilize anti-MHC antibody response which may be useful as part of an anti-HIV-1 vaccination approach.
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Affiliation(s)
- C S Dela Cruz
- Institute of Medical Sciences, Medical Sciences Building, University of Toronto, 1 King's College Circle, Ontario, M5S 1A8, Toronto, Canada
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23
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Dickey C, Ziegner U, Agadjanyan MG, Srikantan V, Refaeli Y, Prabhu A, Sato A, Williams WV, Weiner DB, Ugen KE. Murine monoclonal antibodies biologically active against the amino region of HIV-1 gp120: isolation and characterization. DNA Cell Biol 2000; 19:243-52. [PMID: 10798448 DOI: 10.1089/104454900314519] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The human immunodeficiency virus (HIV)-1 envelope glycoprotein is synthesized as a precursor (gp160) and subsequently cleaved to generate the external gp120 and transmembrane gp41 glycoproteins. Both gp120 and gp41 have been demonstrated to mediate critical functions of HIV, including viral attachment and fusion with the cell membrane. The antigenic variability of the HIV-1 envelope glycoprotein has presented a significant problem in the design of appropriate and successful vaccines and offers one explanation for the ability of HIV to evade immune surveillance. Therefore, the development and characterization of functional antibodies against conserved regions of the envelope glycoprotein is needed. Because of this need, we generated a panel of murine monoclonal antibodies (MuMabs) against the HIV-1 envelope glycoprotein. To accomplish this, we immunized Balb/C mice with a recombinant glycoprotein 160 (gp160) that was synthesized in a baculovirus expression system. From the growth-positive hybridomas, three MuMabs were generated that demonstrated significant reactivity with recombinant gp120 but failed to show reactivity against HIV-1 gp41, as determined by enzyme-linked immunosorbent assay (ELISA). Using vaccinia constructs that synthesize variant truncated subunits of gp160, we were able to map reactivity of all three of the Mabs (ID6, AC4, and AD3) to the first 204 residues of gp120 (i.e., the N terminus of gp120) via Western blot analysis. Elucidation of the epitopes for these Mabs may have important implications for inhibition of infection by HIV-1. Our initial attempts to map these Mabs with linear epitopes have not elucidated a specific antigenic determinant; however, several physical characteristics have been determined that suggest a continuous surface epitope. Although these antibodies failed to neutralize cell-free or cell-associated infection by HIV-1, they did mediate significant antibody-dependent cellular cytotoxicity (ADCC) activity, indicating potential therapeutic utility. In summary, these data suggest the identification of a potentially novel site in the first 200 aa of gp120 that mediates ADCC.
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Affiliation(s)
- C Dickey
- Department of Medical Microbiology and Immunology, University of South Florida College of Medicine, Tampa, Florida, USA
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24
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Gamberg J, Grant M. Cytotoxic T lymphocytes in Human Immunodeficiency Virus type-1 infection Important or impotent? ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s1529-1049(00)00004-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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25
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Whelan JA, Dunbar PR, Price DA, Purbhoo MA, Lechner F, Ogg GS, Griffiths G, Phillips RE, Cerundolo V, Sewell AK. Specificity of CTL Interactions with Peptide-MHC Class I Tetrameric Complexes Is Temperature Dependent. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.163.8.4342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Tetrameric peptide-MHC class I complexes (“tetramers”) are proving invaluable as reagents for characterizing immune responses involving CTLs. However, because the TCR can exhibit a degree of promiscuity for binding peptide-MHC class I ligands, there is potential for cross-reactivity. Recent reports showing that the TCR/peptide-MHC interaction is dramatically dependent upon temperature led us to investigate the effects of incubation temperature on tetramer staining. We find that tetramers rapidly stain CTLs with high intensity at 37°C. We examine the fine specificity of tetramer staining using a well-characterized set of natural epitope variants. Peptide variants that elicit little or no functional cellular response from CTLs can stain these cells at 4°C but not at 37°C when incorporated into tetramers. These results suggest that some studies reporting tetramer incubations at 4°C could detect cross-reactive populations of CTLs with minimal avidity for the tetramer peptide, especially in the tetramer-low population. For identifying specific CTLs among polyclonal cell populations such as PBLs, incubation with tetramers at 37°C improves the staining intensity of specific CTLs, resulting in improved separation of tetramer-high CD8+ cells. Confocal microscopy reveals that tetramers incubated at 37°C can be rapidly internalized by specific CTLs into vesicles that overlap with the early endocytic compartment. This TCR-specific internalization suggests that coupling of tetramers or analogues with toxins, which are activated only after receptor internalization, may create immunotoxins capable of killing CTLs of single specificities.
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Affiliation(s)
- Joseph A. Whelan
- *Nuffield Department of Clinical Medicine, University of Oxford, John Radcliffe Hospital, Headington, Oxford, United Kingdom
| | - P. Rod Dunbar
- †Molecular Immunology Group, Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, United Kingdom; and
| | - David A. Price
- *Nuffield Department of Clinical Medicine, University of Oxford, John Radcliffe Hospital, Headington, Oxford, United Kingdom
| | - Marco A. Purbhoo
- *Nuffield Department of Clinical Medicine, University of Oxford, John Radcliffe Hospital, Headington, Oxford, United Kingdom
| | - Franziska Lechner
- *Nuffield Department of Clinical Medicine, University of Oxford, John Radcliffe Hospital, Headington, Oxford, United Kingdom
| | - Graham S. Ogg
- †Molecular Immunology Group, Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, United Kingdom; and
| | - Gillian Griffiths
- ‡Department of Pathology, Sir William Dunn School, Oxford, United Kingdom
| | - Rodney E. Phillips
- *Nuffield Department of Clinical Medicine, University of Oxford, John Radcliffe Hospital, Headington, Oxford, United Kingdom
| | - Vincenzo Cerundolo
- †Molecular Immunology Group, Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, United Kingdom; and
| | - Andrew K. Sewell
- *Nuffield Department of Clinical Medicine, University of Oxford, John Radcliffe Hospital, Headington, Oxford, United Kingdom
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26
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Price DA, Klenerman P, Booth BL, Phillips RE, Sewell AK. Cytotoxic T lymphocytes, chemokines and antiviral immunity. IMMUNOLOGY TODAY 1999; 20:212-6. [PMID: 10322299 DOI: 10.1016/s0167-5699(99)01447-4] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Evidence that CD8+ CTLs produce chemokines following engagement of viral antigens, and that MIP-1alpha is required for an inflammatory response to virus challenge, suggests that these molecules are key elements in the generation of effective antiviral immunity. Here, David Price and colleagues argue that the antigen-dependent release of chemokines by CTLs provides an elegant mechanism linking localization, amplification and coordination of the antiviral immune response to specific recognition of infected host cells beyond the confines of the lymphoid system.
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Affiliation(s)
- D A Price
- Nuffield Dept of Clinical Medicine and Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, UK OX3 9DU.
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27
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Abstract
Degeneracy rather than unique ligand specificity seems to guide T cell functions. This view has evolved from analyses of T cell development and responses in vivo, as well as studies with synthetic molecular libraries in vitro, and has opened new prospects both for understanding T cell biology and for applied immunology.
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Affiliation(s)
- K Sparbier
- Department of Dermatology, Medical Faculty Charité, Humboldt University, D-10089, Berlin, Germany
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28
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Sewell AK, Gerth UC, Price DA, Purbhoo MA, Boulter JM, Gao GF, Bell JI, Phillips RE, Jakobsen BK. Antagonism of cytotoxic T-lymphocyte activation by soluble CD8. Nat Med 1999; 5:399-404. [PMID: 10202928 DOI: 10.1038/7398] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The CD8 co-receptor is important in the differentiation and selection of class I MHC-restricted T cells during thymic development, and in the activation of mature T lymphocytes in response to antigen. Here we show that soluble CD8alphaalpha receptor, despite an extremely low affinity for MHC, inhibits activation of cytotoxic lymphocytes by obstructing CD3 zeta-chain phosphorylation. We propose a model for this effect that involves interference of productive receptor multimerization at the T-cell surface. These results provide new insights into the mechanism of T-cell activation and evidence that CD8 function is exquisitely sensitive to disruption, an effect that might be exploited by molecular therapeutics.
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Affiliation(s)
- A K Sewell
- Nuffield Department of Clinical Medicine, Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Headington, UK
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